Search Publications
Strong damped Lyman-α absorption in young star-forming galaxies at redshifts 9 to 11
Finkelstein, Steven L.; Arrabal Haro, Pablo; Heintz, Kasper E. +18 more
Primordial neutral atomic gas, mostly composed of hydrogen, is the raw material for star formation in galaxies. However, there are few direct constraints on the amount of neutral atomic hydrogen (H I) in galaxies at early cosmic times. We analyzed James Webb Space Telescope (JWST) near-infrared spectroscopy of distant galaxies, at redshifts ≳8. Fr…
A pulsar in a binary with a compact object in the mass gap between neutron stars and black holes
Cadelano, Mario; Pallanca, Cristina; Freire, Paulo C. C. +22 more
Some compact objects observed in gravitational wave events have masses in the gap between known neutron stars (NSs) and black holes (BHs). The nature of these mass gap objects is unknown, as is the formation of their host binary systems. We report pulsar timing observations made with the Karoo Array Telescope (MeerKAT) of PSR J0514‑4002E, an eccen…
Emission lines due to ionizing radiation from a compact object in the remnant of Supernova 1987A
Fox, O. D.; Blommaert, J. A. D. L.; Larsson, J. +31 more
The nearby Supernova 1987A was accompanied by a burst of neutrino emission, which indicates that a compact object (a neutron star or black hole) was formed in the explosion. There has been no direct observation of this compact object. In this work, we observe the supernova remnant with JWST spectroscopy, finding narrow infrared emission lines of a…
A magnetic massive star has experienced a stellar merger
Smoker, J. V.; Shenar, T.; Sana, H. +13 more
Massive stars (those ≥8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7% of massive stars have observed magnetic fields, the origin of which is debated. We used multi-epoch interferometric and spectroscopic observations …
Sun-like stars produce superflares roughly once per century
Solanki, Sami K.; Notsu, Yuta; Maehara, Hiroyuki +7 more
Stellar superflares are energetic outbursts of electromagnetic radiation that are similar to solar flares but release more energy, up to 1036 erg on main-sequence stars. It is unknown whether the Sun can generate superflares and, if so, how often they might occur. We used photometry from the Kepler space observatory to investigate super…
A magnified compact galaxy at redshift 9.51 with strong nebular emission lines
Koekemoer, Anton M.; Treu, Tommaso; Broadhurst, Tom +21 more
Ultraviolet light from early galaxies is thought to have ionized gas in the intergalactic medium. However, there are few observational constraints on this epoch because of the faintness of those galaxies and the redshift of their optical light into the infrared. We report the observation, in JWST imaging, of a distant galaxy that is magnified by g…
Direct imaging and astrometric detection of a gas giant planet orbiting an accelerating star
Burrows, Adam; Currie, Thayne; Kwon, Jungmi +31 more
Direct imaging of gas giant exoplanets provides information on their atmospheres and the architectures of planetary systems. However, few planets have been detected in blind surveys with direct imaging. Using astrometry from the Gaia and Hipparcos spacecraft, we identified dynamical evidence for a gas giant planet around the nearby star HIP 99770.…
An observed population of intermediate-mass helium stars that have been stripped in binaries
Smith, N.; de Mink, S. E.; Drout, M. R. +4 more
The hydrogen-rich outer layers of massive stars can be removed by interactions with a binary companion. Theoretical models predict that this stripping produces a population of hot helium stars of ~2 to 8 solar masses (M☉), however, only one such system has been identified thus far. We used ultraviolet photometry to identify potential st…
Element abundance patterns in stars indicate fission of nuclei heavier than uranium
Beers, Timothy C.; Placco, Vinicius M.; Holmbeck, Erika M. +9 more
The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and inaccessible to experiments so must be extrapolated by using nucleosynthesis models. We examined el…
Evidence for a radiation belt around a brown dwarf
Pérez-Torres, M.; Guirado, J. C.; Marcaide, J. M. +2 more
Ultracool dwarfs (UCDs) are a category of astronomical objects that includes brown dwarfs and very-low-mass stars. Radio observations of UCDs have measured their brightness as a function of time (light curves) and spectral energy distributions, providing insight into their magnetic fields. We present spatially resolved radio observations of the br…